W. M. Davis — Shaler Memorial Study of Coral Reefs. 249 



stone seems to have been covered by detritus washed down 

 from the valley heads. 



The elevated reef is broadest along the western part of the 

 southern coast, and here it is entered by the branching " lochs " 

 of Pearl harbor, which are neither more nor less than drowned 

 valleys of the most normal kind : hence the elevated reef has 

 stood for a time higher than now ; its first emergence has 

 been followed by a smaller submergence, the difference between 

 the two movements being the twenty or more feet of its 

 present elevation, It is evidently in association with the latest 

 small submergence that the present fringing reef of Oahu has 

 been formed. 



Elevated Reefs in the Fiji Group. — Most of the geological 

 visitors to the Fiji islands have mentioned the elevated reefs of 

 "Wain bay, a small cove a little north of the capital, Suva, on 

 the largest island, Yiti Levu. Some observers, taking account 

 only of these and other high-standing reefs, and neglecting alto- 

 gether the evidence presented by the embayed coast lines, have 

 concluded that the Fiji group is in a region of elevation, and 

 hence that its reefs cannot have been formed by upgrowth 

 during subsidence. The case is by no means so simple as that; 

 for many of the islands give evidence of alternations between 

 emergence and submergence at different dates and by different 

 amounts. 



The two elevated reefs of Walu bay are of small dimensions ; 

 they rise about 100 feet above sea level ; each reef has a thick- 

 ness of about ten or fifteen feet, and lies intercalated between 

 beds of " soapstone " or volcanic muds and rare pebble beds, 

 here dipping 7-10° southward and extending over many 

 square miles of surface. The marine origin of the soapstone 

 is proved by various fossils as well as by the intercalated coral 

 reefs ; hence they have suffered emergence of at least 100 feet. 

 Their seaward dip is believed to be that of original deposi- 

 tion on the advancing front of a river delta, probably that of 

 the Rewa, the largest river of the island, which is now building 

 an extensive delta at present sea level a few miles to the east. 

 The soapstone beds of the emerged delta were nowhere seen in 

 contact with their foundation ; but a few miles east of Suva a 

 creek, that has cut a valley across them, disclosed in its rapids 

 a little distance inland from the soapstone area and a few feet 

 above present sea level, a ledge of volcanic bowlders and 

 cobbles, water-worn and well cemented ; it was therefore 

 concluded that when these cobbles were rounded the island 

 was standing at least as high as now ; that a submergence of a 

 few hundred feet then permitted the deposit of the delta beds, 

 in which the intercalated reefs mark short-lived periods of local 

 coral growth, prevented earlier and later by excess of muddy 



